Mechanical sign engravers typically engrave with engraving or cutting tips attached to a cutting head or chuck rotating at very high speeds--about 10,000 RPM. Engraving begins by plunging the rotating cutting tips into a surface of a sign blank. After the cutting tips have been plunged into the surface of the sign blank, the rotating tips are moved along the surface of the sign blank to engrave a design (i.e. letters, numbers, symbols, or the like). To engrave a design that is not continuous with the previous engraved design, the cutting head is typically retracted to remove the cutting tips from the sign blank, moved to a next location, and unretracted to plunge the cutting tips into the sign blank at the next location.
Chips are generated as the cutting tips rotate and engrave or chip away the desired design in the sign blank. The very high rotational speed of the engravers creates a need for engravers to have effective chip removal systems so that the workplace can remain clean, and so that the engravers may operate without interruptions for clearing chips.
Sign blanks can be made out of various materials including metal, plastic, and wood. A chip removal system should be able to accommodate these various materials. A chip removal system should also be able to accommodate variations in chip size and chip weight because chip size and weight can vary with the type of cutting tip, the engraving depth, and the material of the sign blank.
Prior art chip or debris removal systems have used air flows or vacuums to blow or suck chips away from the cutting region and through a chute or hose into a collection receptacle, such as a cannister. These systems use mechanical fans or vacuums and are expensive and bulky. Typically, these kinds of chip removal systems (such as U.S. Pat. No. 4,915,550, which is for a printed circuit board drill rather than an engraver) have a glider (or pressure foot) surrounding a rotating cutting tool. The glider has an opening through which the cutting tool extends into the workpiece and through which chips, dust, or other debris are blown or drawn by vacuum into the glider. The debris is then blown or sucked out of the glider through a chute leading to a hose and eventually to a collection receptacle. In such systems, the hose is usually long to allow debris to be sufficiently removed from the cutting region so debris does not interfere with the cutting of the workpiece (i.e. sign blank). The long hoses tend to clog easily.
As noted above, chips generated during sign engraving can vary from small, light plastic chips to larger, heavier metal chips. Present chip or debris removal systems are not especially well-suited for mechanical sign engraving because the very large air flows needed to move the large, heavy chips away from the cutting region into a glider, and out of the glider through a hose into the collection receptacle, require expensive fans or vacuums. Such fans and vacuums add significantly to the cost of sign engravers. The cost of fans or vacuums is especially excessive when only small, light chips need to be moved.
It can therefore be appreciated that an improved chip removal system which does not depend upon expensive fans or vacuums to move chips is desirable.